ASSOCIATION BETWEEN ANTIBIOTIC RESISTANCE AND INEFFECTIVENESS IN MUTANT STRAINS OF RHIZOBIUM SPP.

1964 ◽  
Vol 10 (2) ◽  
pp. 221-233 ◽  
Author(s):  
E. A. Schwinghamer
Keyword(s):  
Antibiotic Resistance ◽  
Kanamycin Resistance ◽  
Cross Resistance ◽  
Antibiotic Resistant ◽  
Mutant Strains ◽  
Rapid Dissolution ◽  
Rhizobium Spp ◽  
Resistant Mutants ◽  
Neomycin Resistance ◽  
Antibiotic Resistant Mutants

Loss of effectiveness was found to be closely associated with mutation to viomycin resistance and neomycin resistance in strains representing three cross-inoculation groups of Rhizobium—R. leguminosarum, R. trifolii, and R. meliloti. Twenty-nine of 33 mutant clones, selected from 11 normally effective parent strains for resistance to viomycin, were uniformly ineffective. Both viomycin resistance and ineffectiveness remained unchanged in clones reisolated from nodules. Fifteen of 16 clones selected for neomycin resistance from eight normally effective strains were also ineffective, fn contrast, loss of effectiveness occurred only infrequently in clones resistant to kanamycin or polymyxin, and was not observed at all in streptomycin-resistant mutants. Cytologically, ineffective nodules were characterized by rapid dissolution of bacteroid-containing tissue. Ability to form nodules (infectiveness) on the homologous host was retained in all antibiotic-resistant mutants. Full cross resistance was noted for strains selected for resistance to viomycin and neomycin. Kanamycin resistance conferred resistance to neomycin but not to viomycin. Implications of the marker-associated changes are considered in relation to some problems in Rhizobium genetics and physiology.

scholarly journals NEW ANTIBIOTIC RESISTANCE LOCI IN THE RIBOSOMAL REGION OF YEAST MITOCHONDRIAL DNA

Genetics ◽  
1980 ◽  
Vol 94 (1) ◽  
pp. 69-92
Author(s):  
Jeffrey A Knight
Keyword(s):  
Mitochondrial Dna ◽  
Antibiotic Resistance ◽  
Resistant Mutant ◽  
Cross Resistance ◽  
Antibiotic Resistant ◽  
Resistance Patterns ◽  
Genetic Techniques ◽  
Resistant Mutants ◽  
Yeast Mitochondrial Dna ◽  
Antibiotic Resistant Mutants

ABSTRACT A large number of mitochondrial antibiotic-resistant mutants have been isolated following mutagenesis with manganese. These include several different phenotypic classes of mutants, as distinguished by cross-resistance patterns, that have been found to be allelic at capl or eryl; some have been found to be heteroalle1ic.—Seven chloramphenicol-resistant mutants have been identified that are nonallelic by recombination tests with the three loci (capl, spil and eryl) previously identified in the ribosomal region. Four of these are allelic with each other and define a new locus, cap3; two others are allelic and define another new locus, cap2; the seventh maps at yet a different locus, cap4. One new spiramycin-resistant mutant has been identified that defines still another new locus, spi2. A variety of genetic techniques have been used to map these loci within the ribosomal region of the mitochondrial genome.—Manganese has been shown to be effective in inducing the mutation from ω- to ωn in many mutants that experience a simultaneous mutation at the closely linked capl locus. The ωn mutation has also been described in the capl mutant, and this locus has been shown to be more closely linked to o than capl is to ω.

scholarly journals Associations between Bacteriophage Resistance and Antibiotic Resistance Phenotypes in Laboratory and Clinical strains of Salmonella Typhimurium

2019 ◽  
Author(s):  
Md Jalal Uddin ◽  
Juhee Ahn
Keyword(s):  
Antibiotic Resistance ◽  
Salmonella Typhimurium ◽  
Multidrug Resistant ◽  
Resistant Bacteria ◽  
Bacteriophage P22 ◽  
Antibiotic Resistant ◽  
Antibiotic Susceptibilities ◽  
Resistant Mutants ◽  
Mutant Frequency ◽  
Antibiotic Resistant Mutants

Abstract Background Bacteriophages have received great attention as alternative over antibiotics due to the host specificity. Therefore, this study was designed to evaluate the associations between bacteriophage-insensitive (BI) and antibiotic-resistant mutants of Salmonella Typhimurium strains. Bacteriophage-sensitive Salmonella Typhimurium ATCC 19585 (BSSTWT), ciprofloxacin-induced S. Typhimurium ATCC 19585 (BSSTCIP), S. Typhimurium KCCM 40253 (BSSTLAB), and clinically isolated multidrug-resistant S. Typhimurium CCARM 8009 (BSSTMDR) were used to induce the bacteriophage-insensitive mutants (BISTWT, BISTCIP, BISTLAB, and BISTMDR) against bacteriophage P22. Results The numbers of BSSTWT, BSSTCIP, and BSSTLAB were reduced by P22 (>3 log), while the least lytic activity was observed for BSSTMDR. BSSTWT treated with P22 showed the large variation in the cell state (CV>40%) and highest mutant frequency (62%), followed by 25% for STCIP. The least similarities between BSSTWT and BISTWT were observed at P22 and PBST-13 (<12%). The antibiotic susceptibilities were not significantly changed or slightly increased against BISTWT, BISTCIP, BISTLAB, and BISTMDR. The relative expression levels of bacteriophage-binding receptor-related genes (btuB, fhuA, fliK, fljB, ompC, ompF, rfaL, and tolC) were decreased in BISTCIP and BSSTMDR. Conclusion The results could pave the way for the application of bacteriophages as an alternative to control antibiotic-resistant bacteria.

scholarly journals The spatial profiles and metabolic capabilities of microbial populations impact the growth of antibiotic-resistant mutants

2015 ◽  
Vol 12 (107) ◽  
pp. 20150018 ◽  
Author(s):  
Karishma S. Kaushik ◽  
Nalin Ratnayeke ◽  
Parag Katira ◽  
Vernita D. Gordon
Keyword(s):  
Antibiotic Resistance ◽  
Bacterial Species ◽  
Global Scale ◽  
Antibiotic Resistant ◽  
Wide Range ◽  
Nutrient Environment ◽  
Resistant Mutants ◽  
Cell Densities ◽  
Opportunistic Human Pathogen ◽  
Antibiotic Resistant Mutants

Antibiotic resistance adversely affects clinical and public health on a global scale. Using the opportunistic human pathogen Pseudomonas aeruginosa , we show that increasing the number density of bacteria, on agar containing aminoglycoside antibiotics, can non-monotonically impact the survival of antibiotic-resistant mutants. Notably, at high cell densities, mutant survival is inhibited. A wide range of bacterial species can inhibit antibiotic-resistant mutants. Inhibition results from the metabolic breakdown of amino acids, which results in alkaline by-products. The consequent increase in pH acts in conjunction with aminoglycosides to mediate inhibition. Our work raises the possibility that the manipulation of microbial population structure and nutrient environment in conjunction with existing antibiotics could provide therapeutic approaches to combat antibiotic resistance.

scholarly journals Rapid and robust evolution of collateral sensitivity in Pseudomonas aeruginosa antibiotic-resistant mutants

2020 ◽  
Vol 6 (32) ◽  
pp. eaba5493
Author(s):  
Sara Hernando-Amado ◽  
Fernando Sanz-García ◽  
José Luis Martínez
Keyword(s):  
Cystic Fibrosis ◽  
Pseudomonas Aeruginosa ◽  
Antibiotic Resistance ◽  
Rational Design ◽  
Antibiotic Resistant ◽  
Trade Off ◽  
Collateral Sensitivity ◽  
Trade Offs ◽  
Resistant Mutants ◽  
Antibiotic Resistant Mutants

The analysis of trade-offs, as collateral sensitivity, associated with the acquisition of antibiotic resistance, is mainly based on the use of model strains. However, the possibility of exploiting these trade-offs for fighting already resistant isolates has not been addressed in depth, despite the fact that bacterial pathogens are frequently antibiotic-resistant, forming either homogeneous or heterogeneous populations. Using a set of Pseudomonas aeruginosa-resistant mutants, we found that ceftazidime selects pyomelanogenic tobramycin-hypersusceptible mutants presenting chromosomal deletions in the analyzed genetic backgrounds. Since pyomelanogenic resistant mutants frequently coexist with other morphotypes in patients with cystic fibrosis, we analyzed the exploitation of this trade-off to drive extinction of heterogeneous resistant populations by using tobramycin/ceftazidime alternation. Our work shows that this approach is feasible because phenotypic trade-offs associated with the use of ceftazidime are robust. The identification of conserved collateral sensitivity networks may guide the rational design of evolution-based antibiotic therapies in P. aeruginosa infections.

Using spontaneous antibiotic-resistant mutants to assess competitiveness of bradyrhizobial inoculants for nodulation of soybean

1998 ◽  
Vol 44 (8) ◽  
pp. 753-758 ◽  
Author(s):  
Martha E Ramirez ◽  
Daniel W Israel ◽  
Arthur G Wollum II
Keyword(s):  
Parental Strain ◽  
Field Experiments ◽  
Antibiotic Resistant ◽  
Rooting Zone ◽  
Soil Systems ◽  
Yeast Extract Mannitol ◽  
Soil Media ◽  
Resistant Mutants ◽  
Cape Fear ◽  
Antibiotic Resistant Mutants

Spontaneous mutants (3/parental strain) of soybean bradyrhizobia resistant to streptomycin and erythromycin were selected from strains isolated from bradyrhizobial populations indigenous to Cape Fear and Dothan soils. These were used to evaluate (i) the validity of using antibiotic-resistant mutants to make inferences about the competitiveness of parental strains in soil environments and (ii) the recovery of strains in nodules after inoculation of soybeans grown in soils with indigenous bradyrhizobial populations. Streptomycin and erythromycin resistances of all mutants were stable after approximately 27 generations of growth in yeast extract - mannitol medium, but 33% of the mutants lost resistance to erythromycin upon passage through nodules. Only 17% of the mutants were as competitive as their parental strain when inoculated in a ratio near 1:1 in vermiculite. Four of 10 mutants, which differed in competitiveness from their parental strain in vermiculite, had competitiveness against the soil populations equal to that of their parental strain. Therefore, assessment of competitiveness of mutants and parental strains in non-soil media may not accurately reflect their competitiveness in soil systems. For both the Cape Fear and Dothan soils, recovery of a given mutant from nodules of field-grown plants was always lower than from nodules of plants grown in the greenhouse. Inoculation of the entire rooting zone in the greenhouse experiment and of only a portion of the rooting zone in the field experiments may account for this difference in recovery. Techniques that increase the volume of soil inoculated may enhance nodulation by inoculant strains.Key words: Bradyrizobium, antibiotic resistance, competition.

scholarly journals Slow growth determines nonheritable antibiotic resistance in Salmonella enterica

2019 ◽  
Vol 12 (592) ◽  
pp. eaax3938 ◽  
Author(s):  
Mauricio H. Pontes ◽  
Eduardo A. Groisman
Keyword(s):  
Bacterial Population ◽  
Slow Growth ◽  
Large Fraction ◽  
Signaling Molecules ◽  
Antibiotic Resistant ◽  
Phenotypic Changes ◽  
Resistant Mutants ◽  
Persistent Bacteria ◽  
Small Subpopulation ◽  
Antibiotic Resistant Mutants

Bacteria can withstand killing by bactericidal antibiotics through phenotypic changes mediated by their preexisting genetic repertoire. These changes can be exhibited transiently by a large fraction of the bacterial population, giving rise to tolerance, or displayed by a small subpopulation, giving rise to persistence. Apart from undermining the use of antibiotics, tolerant and persistent bacteria foster the emergence of antibiotic-resistant mutants. Persister formation has been attributed to alterations in the abundance of particular proteins, metabolites, and signaling molecules, including toxin-antitoxin modules, adenosine triphosphate, and guanosine (penta) tetraphosphate, respectively. Here, we report that persistent bacteria form as a result of slow growth alone, despite opposite changes in the abundance of such proteins, metabolites, and signaling molecules. Our findings argue that transitory disturbances to core activities, which are often linked to cell growth, promote a persister state regardless of the underlying physiological process responsible for the change in growth.

scholarly journals Antibiotic-Resistant Gram-Negative Bacteria in Birds From the Brazilian Atlantic Forest

The Condor ◽  
2003 ◽  
Vol 105 (2) ◽  
pp. 358-361 ◽  
Author(s):  
Andréa M. A. Nascimento ◽  
Luciana Cursino ◽  
Higgor Gonçalves-Dornelas ◽  
Andrea Reis ◽  
Edmar Chartone-Souza ◽  
...  
Keyword(s):  
Antibiotic Resistance ◽  
Kanamycin Resistance ◽  
Minas Gerais ◽  
Resistant Bacteria ◽  
Gram Negative Bacteria ◽  
Brazilian Atlantic Forest ◽  
Antibiotic Resistant ◽  
Gram Negative ◽  
Resistant Phenotype ◽  
Animal Farms

Abstract We evaluated the antibiotic resistance of bacteria isolated from cloacal swabs of wild birds collected with mist nets in the Jequitinhonha river valley, in the state of Minas Gerais, Brazil. A total of 191 isolates from 19 individuals of 16 species was obtained and tested for resistance to five antibiotics. At Salto da Divisa 97% of the isolates exhibited a resistant phenotype, and resistance to more than one antibiotic was frequent (71%). At Jequitinhonha 36% of isolates were resistant, but 94% showed resistance to only one antibiotic. Of the five antibiotics tested, resistance to ampicillin was most frequent (in both areas), whereas kanamycin resistance was found in only one isolate. The data here obtained and other data reported in the literature show that the general premise that antibiotic-resistant bacteria arise primarily in hospitals or animal farms should be reconsidered. Bactérias Gram-Negativas Resistentes a Antibióticos em Aves da Mata Atlântica Brasileira Resumo. Avaliamos a resistência a antibióticos de bactérias isoladas por swab cloacal em aves selvagens capturadas com redes de neblina em duas regiões do Vale do Rio Jequitinhonha, Minas Gerais, Brasil. Foram obtidos 191 isolados de 19 indivíduos de 16 espécies e foi testada a resistência desses isolados a cinco antibióticos. Em Salto da Divisa, 97% dos isolados exibiram fenótipo resistente e foi freqüente (71%) a resistência a mais de um antibiótico. Em Jequitinhonha, 36% dos isolados exibiram fenótipo resistente, dos quais 94% apresentaram resistência a apenas um antibiótico. Em ambas as áreas, a maioria dos isolados apresentou resistência à ampicilina, enquanto somente um único isolado foi resistente à canamicina. Os dados aqui obtidos e outros relatados na literatura mostram que a premissa geral de que bactérias resistentes a antibióticos surgem principalmente em hospitais ou fazendas de animais deve ser reconsiderada.

Competition for nodulation of field-grown soybeans by strains of Rhizobium fredii

1986 ◽  
Vol 32 (2) ◽  
pp. 183-186 ◽  
Author(s):  
Thomas J. McLoughlin ◽  
Scott G. Alt ◽  
P. Ann Owens ◽  
Corrine Fetherston
Keyword(s):  
Bradyrhizobium Japonicum ◽  
Indigenous Population ◽  
Growing Season ◽  
Indigenous Populations ◽  
First Year ◽  
Antibiotic Resistant ◽  
Rhizobium Fredii ◽  
Glycine Max L ◽  
Resistant Mutants ◽  
Antibiotic Resistant Mutants

Nodulation of Glycine max (L) Merr. by six Rhizobium fredii strains was measured in two Midwestern fields containing high indigenous populations of Bradyrhizobium japonicum (3 × 105/gm soil). The soils were inoculated with antibiotic-resistant mutants using liquid inoculum at two levels on soybean cv. Peking and cv. Jacques 130. Strain establishment was measured 40 days after planting. In the first year, USDA206, USDA217, and USDA257 were the most competitive strains, occupying greater than 50% of the nodules on cv. Peking in both soils. None of the strains were competitive on Jacques 130. In the second growing season, all nodules were formed by the indigenous population on both cultivars, suggesting that these fast-growing strains do not persist in Midwestern soils.

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